It is conventional to provide electrically operated roof top air conditioning units for buildings, with such units each having a refrigerant compressor driven by an electric motor. If the building is located in a part of the world which also requires heating facilities, a separate furnace is provided, which may be a natural gas or a fuel oil furnace.
In some parts of the United States, as well as the world, electricity is relatively costly, compared with the cost of natural gas or fuel oil. Thus, it would be economical in such areas to drive the refrigerant compressor with an internal combustion engine which operates on natural gas or fuel oil. Such a unit may include provisions for incorporating an optional natural gas or fuel oil furnace, so that natural gas or fuel oil will be the major fuel for both heating and cooling. Electrical requirements would thus be minimal, even when electric motors are provided for operating evaporator blowers, to make it unnecessary to operate the engine when only air circulation is required.
A major concern of such an arrangement is the transmission of vibration from the internal combustion engine into the building roof structure, and the accompanying emission of noise into the building. It is an object of the present invention to provide an air conditioning unit having a prime mover in the form of an internal combustion engine which is constructed to reduce vibration transmitted into the building roof structure and to reduce noise transmissions into the building, to acceptable levels.